From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Tue, 16 Jun 2020 00:46:44 +0000 (-0700)
Subject: bpo-40985: Show correct SyntaxError text when last line has a LINECONT (GH-20888)
X-Git-Tag: v3.9.0b4~79
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=097b8b6d52e3d4991c68dce74f182718dc0eab9c;p=thirdparty%2FPython%2Fcpython.git

bpo-40985: Show correct SyntaxError text when last line has a LINECONT (GH-20888)


When a file ends with a line that contains a line continuation character
the text of the emitted SyntaxError is empty, contrary to the old
parser, where the error text contained the text of the last line.
(cherry picked from commit 113e2b0a07c72c0d5e3489076afb14f6b3ad1049)

Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
---

diff --git a/Lib/test/test_eof.py b/Lib/test/test_eof.py
index bebad3106119..51cbbd8eed66 100644
--- a/Lib/test/test_eof.py
+++ b/Lib/test/test_eof.py
@@ -52,10 +52,14 @@ class EOFTestCase(unittest.TestCase):
             file_name = script_helper.make_script(temp_dir, 'foo', '\\')
             rc, out, err = script_helper.assert_python_failure(file_name)
             self.assertIn(b'unexpected EOF while parsing', err)
+            self.assertIn(b'line 2', err)
+            self.assertIn(b'\\', err)
 
             file_name = script_helper.make_script(temp_dir, 'foo', 'y = 6\\')
             rc, out, err = script_helper.assert_python_failure(file_name)
             self.assertIn(b'unexpected EOF while parsing', err)
+            self.assertIn(b'line 2', err)
+            self.assertIn(b'y = 6\\', err)
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-06-15-16-29-55.bpo-40985.IIN_xX.rst b/Misc/NEWS.d/next/Core and Builtins/2020-06-15-16-29-55.bpo-40985.IIN_xX.rst
new file mode 100644
index 000000000000..e07134c7166a
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-06-15-16-29-55.bpo-40985.IIN_xX.rst	
@@ -0,0 +1 @@
+Fix a bug that caused the :exc:`SyntaxError` text to be empty when a file ends with a line ending in a line continuation character (i.e. backslash). The error text should contain the text of the last line.
diff --git a/Python/errors.c b/Python/errors.c
index 5d1725679c4b..87af39d527a5 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -1648,16 +1648,18 @@ err_programtext(PyThreadState *tstate, FILE *fp, int lineno)
 {
     int i;
     char linebuf[1000];
-
-    if (fp == NULL)
+    if (fp == NULL) {
         return NULL;
+    }
+
     for (i = 0; i < lineno; i++) {
         char *pLastChar = &linebuf[sizeof(linebuf) - 2];
         do {
             *pLastChar = '\0';
             if (Py_UniversalNewlineFgets(linebuf, sizeof linebuf,
-                                         fp, NULL) == NULL)
-                break;
+                                         fp, NULL) == NULL) {
+                goto after_loop;
+            }
             /* fgets read *something*; if it didn't get as
                far as pLastChar, it must have found a newline
                or hit the end of the file; if pLastChar is \n,
@@ -1665,6 +1667,8 @@ err_programtext(PyThreadState *tstate, FILE *fp, int lineno)
                yet seen a newline, so must continue */
         } while (*pLastChar != '\0' && *pLastChar != '\n');
     }
+
+after_loop:
     fclose(fp);
     if (i == lineno) {
         PyObject *res;